As art relating to a method and mold system for injection molding a composite product made of resins of different properties, there are an injection molding method of a composite product and a mold system for injection molding a composite product (see for example Patent Document 1). This Patent Document 1 uses a primary molding unit to mold a primary molded part by primary molding, switches a movable mold holding the primary molded part with a movable mold of a secondary molding unit, and uses a secondary molding unit having the primary molded part as an insert to mold a secondary molded part by secondary molding and thereby simultaneously proceed with the primary molding and secondary molding.
According to the injection molding method and mold system of Patent Document 1 described above, molds are juxtaposed to a fixed platen and movable platen. Therefore, a large sized fixed platen and movable platen become necessary and the shape of the injection molding machine also becomes larger, so this is not suitable for molding a large sized molded article. Further, in order to mold a vehicular use transparent member or other large sized and thin sheet shaped molded article without deviation in sheet thickness and with a high precision, it must be performed by compression molding. According to the technology of Patent Document 1 explained above, however, the clamping operations of the primary molding and secondary molding can only be performed simultaneously and in addition under the same conditions. Therefore, it is substantially impossible to individually perform the compression molding operations by individual mold systems. In particular, the molding method of Patent Document 1 cannot be applied to composite molding of a vehicular use transparent member etc. where compression molding is essential for molding the thin sheet window by the primary molding, but compression molding is not needed for molding the frame at the outer circumference of the window by the secondary molding.
Further, there is a system for producing an injection molded article comprising at least two plastic melts (see for example Patent Document 2). This Patent Document 2 is a type having a fixed mold mounting plate stationarily attached to a machine frame, a mold mounting plate able to move along at least four horizontal tie rods arranged between the fixed mold mounting plate and a counter pressure plate stationarily attached to the machine frame and extending substantially horizontally, and, between them, an additional mold mounting device movable with respect to the mold mounting plate and rotatable around an axis of rotation aligned perpendicular to the longitudinal axis of the horizontal tie rods. The mold mounting device holds mold halves cooperating with mold halves of the mold mounting plates on at least two side surfaces aligned with a spacing from each other and parallel to the axis of rotation. Each of the mold mounting plates is provided with at least one opening. Plasticizing and injection units are connected via these openings to one or more sprue channels in the mold halves held by the mold mounting plates. The two mold halves are simultaneously or directly successively supplied with one or more plastic melts from the injection units connected to the mold halves. Accordingly, according to Patent Document 2 explained above, the mold halves are arranged on the same axis. Therefore, the problem of the larger size of the injection molding machine in Patent Document 1 explained above is solved, but the problem of compression molding being impossible is not solved.
[Patent Document 1] Japanese Patent Publication (A) No. 2002-225078
[Patent Document 2] Japanese Patent Publication (A) No. 11-105072